1. Warm the olive oil in a large pot over medium heat. Add the shallots, thyme and 1/4 teaspoon salt; cover and cook, stirring a few times, until shallots are translucent, about 6 minutes.
2. Mix in the chard, tomatoes, chickpeas, vegetable stock, and cayenne; cover and simmer 10 minutes.
3. Remove thyme and season stew with the lemon juice. Add the pinch of salt and the black pepper to taste; serve with garlic toasts if desired.